<!DOCTYPE html>
<html>
<head>
  <meta http-equiv="content-type" content="text/html; charset=UTF-8">
  <script type="text/javascript">
    function show() {
      var results = /\?topic=(.+)$/.exec(window.document.location);
      var topic = decodeURIComponent(results[1].replace(/\+/g, " "))
      var node = document.getElementById("topic");

      node.textContent = topic;
    }
  </script>
</head>

<body onload="show()">
  <div id="topic"></div>
</body>
</html>
